<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        .big-box {
            width: 1000px;
            height: 500px;
            background-color: lightslategrey;
            /* 变成弹性盒 */
            display: flex;
            /* 内容换行 */
            flex-flow: wrap;
            /* 内容对齐方式 居中*/
            /* justify-content: center; */
            /* 两边的间隔相等 */
            /* justify-content: space-around; */
            /* 左右对齐 */
            justify-content: space-between;
            /* justify-content: space-evenly; */
            /* 居中 */
            /* align-items: center; */
            /* 右对齐 */
            /* align-items: flex-end; */
            /* 默认 */
            /* align-items: flex-start; */
            /* 主轴为垂直方向 */
            flex-direction: column;
            /* 终点对齐 */
            /* align-items: flex-end; */
            /* 起点对齐 */
            align-items: flex-start;
        }

        .box {
            width: 300px;
            height: 200px;
            background-color: lime;
        }
    </style>
</head>

<body>
    <div class="big-box">
        <div class="box"></div>
        <div class="box"></div>
        <div class="box"></div>
        <div class="box"></div>
        <div class="box"></div>
    </div>
</body>

</html>